Several structural applications require filling of relatively small cross-sectional area elongated channels with foam, preferably a multi-component foam, such as polyurethane. The purposes of the foam "core" includes, for example, providing a thermal barrier, sound attenuation, improved structural rigidity and impeding air infiltration. The method of this invention is particularly adapted to a commercial mass production method of substantially completely filling such elongated channels, while reducing labor costs.
The method of this invention will be described in relation to the filling of the channels of an extruded lineal, such as used by the window and sliding door industry. It will be understood, however, that the method of this invention is also suitable for many other applications which require filling of relatively small cross-sectional are elongated channels with resin foam. Extruded lineals used by the window industry, for example, are generally formed of polyvinyl chloride (PVC). The extruded lineals are commercially available in 14-foot lengths or longer and generally include two or more parallel channels. The channels to be filled have a cross-sectional area ranging from about 0.5 square inches to 2 square inches, or greaTer. The channels may be filled with a relatively rigid polyurethane foam to improve the structural rigidity of the relatively flexible PVC lineals, impede air infiltration and to provide a thermal barrier and reduce sound attenuation. It is generally difficult to use a pre-formed foam core because the shape of the channels may be complex, and the shape varies from channel to channel. Pre-formed or pre-cut foam cores have, however, been used in such applications, where the foam core is cut to the desired shape and then telescopically inserted into the channel.
The two presently preferred methods of filling the channels of an extruded lineal may result in substantial voids throughout the length of the channels, reducing the advantages of filling the channels with foam. The preferred foam for extruded lineals is a multi-component polyurethane foam, and the channels are filled with a spray or pour gun. Both methods require movement of either the application gun or the lineal, requiring two or three operators. In one method, for example, a conventional foam application gun, such as a Gusmer Model D spray gun or AR-250 pour gun, is fitted with a metal tubular extension having a length of about three feet or longer. The extension is inserted into one open end of the lineal channel, which is laid flat on a horizontal surface. The liquid foamable polyurethane is then poured into the channel. The channel is then moved away from the gun to fill one-half of the channel of the lineal with polyurethane foam. The process is then repeated from the opposite open end of the lineal, to fill the entire channel with polyurethane foam. As will be understood, this method requires two or three operators, and the lineal must be filled from both ends, resulting in substantial labor costs.
In a second commercial method, a polyurethane pour gun is fitted with a flexible hose which is inserted several feet into the lineal channel. The channel is supported on a horizontal surface. The hose is then withdrawn as the liquid polyurethane foam is poured into the lineal channel, allowing the filling of the lineal channel from one end. The rate of withdrawal of the hose must be accurately controlled, and one operator withdraws the hose as the second operator operates the pour gun. As described, both methods may result in substantial voids throughout the lineal channel or inconsistent filling, and both methods require at least two operators.
The need therefore remains for a method of efficiently filling an elongated channel, such as the channels of an elongated lineal, which eliminates or substantially eliminates voids and which preferably requires only one operator. In the method of the present invention, elongated channels, such as the channels of extruded lineals, may be filled with foam, including polyurethane foam, by one operator, substantially eliminating voids in the foam core. The elongated channel may be filled from one end and takes a few seconds to complete. The method of this invention does not require fixtures or gun extensions, such as a tube or probe, and the method is not very sensitive to operator control.